Countercurrent lixiviator



May 1924.

J. W. TURRENTINE A COUNTERcURRszm LIXIVIATOR Filed oct; 25 1922 ESI uml .0.02 20kg-LGT .Ng ldmm! .Vlelvlllr ull n.. SSL

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Patented May 6, 1924.

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JOHN W. '.iUBRIEN'IINIEI,l OF SANTA BARBARA, CALIFORNIA, DEDICATED, BY MESNE ASSIGNMENTS,

T0 THE PEOPLE OF THE UNITED STATES FOR THEIR FREE USE COUNTERCURRENT LIXIVIATR.

`Application led October 25, 1922. Serial No. 596,890.

(FILED UNDER THE ACT 0F MARCH 3, 1883, 22 STAT. 1. 625.) I-

To all whom t may concern."

Be it known that I, JOHN TW. TURRENTINE, a citizen of the United States, and an employee of the United States Department of 5 Agriculture, residing at Santa Barbara, Calif., have invented a new and useful Countercurrent 'Lixiviator, of which the following is a full, clear, and exact specification.

This-application'is made under the act of March 3, 1883, chapter 143 (22 Stat. 625)', and the invention herein described and claimedvmay be used by the Government of the United States or any of its ocers or employees in the pursuit of work for the Government, or by any other person in the United States without payment to mev of -any royalty thereon. v

This invention relates to an automatic, continuous, multiple-stage, countercurrent lixiviator, making use of the vacuum vfiltration principle.

The princi le of countercurrent leaching is old, as is a so the princi le of vacuum til- B tration. rThe originality t at is claimed for the present invention is that it is a combination of the two. Being that, it makes ossible the exact and ecient filterin aforded by the most improved vacuum li ters, and at the same time yields all of the eat and sometimes essential economies o the countercurrent application of a solvent. There are instances that may be cited where' edorts to'utilize raw. materials have been abandonedbecause of the impossibility of securing highly concentrated solutions by oldextraction methods. l

My invention is a plicable to the whole great list 'of material; that ma be filtered on rotary ilters, and thus allor s a wide-extension of the field over which countercurrent extraction is possible. Being elastic, -it can be applied as easily to extractions reoiiring a arge number oit-applications of t e solvent as to those requiring onl a few. 01d methods of countercurrent leac ing are slow, intermittent, and involve. generally a high cost for installation, require a large door space, and where corrosive solvents are employed are practically prohibitive on ac count of the cost of non-corrosive materials of construction. The employment' of my invention DVOlVeS amoderate expense for installation, operation and upkee has a large proportional capacity; may de compactly built, and occupies a small iioor space; and easilyv admits of acid-proof construction.

The most efficient extraction is obtainable for a given volume of -solvent when the solid to be extracted is vigorously stirred With ythe solvent at the optimum temperature, and then filtered. The solvent is removed as completely as possible, and a fresh portion added; each time the smallest amount of solvent being applied as still allows the mixture to flow. This method of applying a solvent is made possible by my invention, and it is claimed that itis the only system that does make this possible in a continuous and automatic manner.

The invention is shown in the accom anying drawing which consists of one gure,

'quirements 4 of the application.

The type of agitator A, A and A found advantageous is one built in the shape of a trough H with agitating paddles F arranged on a shaft Gr extending'the long axis of the trough H. Since the suspension of the material undergoing extraction in the solvent forms a sludge which iiows through the agitator A, A and A" the`9-0 length of the trough H and the speed of flow of the slud e determines the length of time each partie e of the solid is forced to remain in contact with the extracting agent.

However, the shape of the agitator may be left to the dictates ofthe application and the method of stirring likewise. The agitator may be opened or closed, or may be provided with hinged lids so that it may be opened or closed. Likewise, its material of ma construction may be, as -required, of wood, or steel, or acid-proof metal, or rovided with acid-proof coatings. It may e steamjacketed or heated with steam coils, or insulated or refrigerated, providing for the optimum temperature conditions.

end. Thus, the fresh solids are al The filters B, B and B may be an of the continuous filters, but ispreferah y a rotary, vacuum filter with several vacuum compartments and one compartment to receivecompressed air or steam to aid in the removal of the filter cake.

For viscous liquids too thick and sluggish to be filtered by pressures limited to the atmosphere, high speed centriiugals or cen-s triztugal or pressure filters may be substituted for the vacuum filters. lln cases Where these are not continuous, the dow of sludge from the agitator to the filter is suspended While the lter is being discharged; during which short interval the agitator is re uired to act as a reservoir.

upplemental apparatus, such as vacuum and solvent pumps D, D', and D",

vacuum receivers E, E and E, lines and valves, may be of a standard or special type as desired.4 A f ln construction, the various units are placed in the series in echelon order with respect to one another, as likewise are the agitator and filter' in the unit with res ect to each other. Thus, the mixture of so ids undergoing extractionA and the solvent, forming a sludge, Hows by gravit from the agitator into the filter tank. An likewise, the iiltered solids fall by gravity trom the lter of one unit into the agitator of the next unit. This taires place continuously and automatically. The iiltrate or solvent removed by ltration is delivered from the filter ofone unit to the agitator of the next one above itn y"lhus, the solids pass down hill by gravity, and the solvent is passed up hill by means of pumps.

In application, the solid to -be extracted is admitted to the agitator of the unit at one end of the system and the fresh solvent to the agitator of the unit at the o posit ixe with the solvent delivered from the filter of the next unit, which solvent has traversed the entire series of agitators and filters and has come successively into intimate contact with the solids in every preceding agitator, and has become more and more concentrated in the com ounds to be dissolvedl as it has advanced jtli)rough the system. Finally. comin into contact with the fresh, untreated so ds, unless lalread saturated, it dissolves that part of the so uble solids moet easily dissolved, and is then ready to be discharged as the spentsolvent or as the practica ly saturated solution ready for further processing.

At the op osite end, the fresh solvent is admixed with the solids delivered from the lter of the next unit; and, these solids, having traversed the entire series ci agitators, have come succively into intimate contact with the soient in every stator, and have s lthe latter so as to atlmit o incassa ready completely extracted, they yield that part of the extractable material most diliicult to dissolve; and are then ready to be discharged as the spent solids or as the completely extracted material vready for further processin Each unit delivers a solution'somewhat more concentrated than the succeeding one, and a filter cake of solids somewhat more nearly completely extracted than the preceding one.

The system is as applicable to the development of a concentrated solution Jfor further processing or the complete exhaustion of a solvent as to the complete extraction of a solid. It can be made to do both simultaneously. lt does both continuously and automatically.

This process has been em loyed successfully in the lixiviation of ire p'fcharcoal and its eihcacy abundantly demonstrated.

l claim: I

A continuous, automatic countercurrent lixiviator comprisin a series ot units, the same being dispose in echelon order with respect to one another and each being composed of an extractilon chamber and ilter, the-former being p aced preferablyabove gravity flow of the contents of the e traction chamber upon the filter, means fo introducing treshsolvent intoV the extraction chamlier of the lill@ lowest unit of the series, means for introducing into said extraction chamber nearly completely extracted and filtered solids frompthe filter of the next preceding and higher unit and which have traverse said series from the highest to the lowest unit undergoing progressive extraction the while,

means for mixing said solvent with said solids, means for'discharging the mixtrre of said solvent and solids from the extraction chamber u on the lter of said unit, means 'for disc ar 'n the completely extracted and filtered1 siids from said filter, means or lifting the solvent from said filter and discharging same' into the extraction chamber of the next higher unit, means for dischargin into said extraction chamber the parta y extracted and .liltered solids for the next preceding and higher unit, means for-mixing said solvent and solide, and repeating said operation with respect to the other units of said series until the series or units trom the lowest to the highest have beentraversed by the solvent, the selvent the While becoming progressively more concentrated in compounds extracted from the solids, means for'. introducing h' solids from which compound to be extreated' late. e extraction eher et' the succeeding unit f which has traversed the series of units upward from the lowest to the hlghest inclusive, means for mixing sa1d solids and solvent, means for discharging mixture of said solids' and solvent upon the filter of said highest unit, means for dischar ing the practically spent solvent from the filter of each unit5 means for discharging the partially extracted and Yfiltered solids from 4the filter of each unit into the extraction chamber of next lower and succeeding unit, means for i-ntroducingdnto said extraction chamber the partially spent solvent'from the filter of the unit next below and following the said unit, and means forA agitating the mixture of said solids and solvent in the extraction `chamber of each unit.

JOHN W. TURRENTINE. 

